The rise of CSC theory, some specific CSC markers were being discovered to identify putative CSCs, and ALDH1 is becoming to act as a CSC marker in the CSC studies of variable tumor types in vitro and in vivo. Epithelial-to-mesenchymal transition (EMT) is an important driver of tumor invasion and metastasis, which may be a feature of CSC. Compared to ALDH1(-) EMT cells, only ALDH1(+) EMT cells had